<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<body>

<div id="app">

    <button v-on:click="sayHi">click me</button>

</div>

<!--1.导入vue.js-->
<script src="https://cdn.jsdelivr.net/npm/vue@2.5.21/dist/vue.min.js"></script>

<script>
    var vm = new Vue({
        el:"#app",
        data:{
            message: "狂神说java"
        },
        methods:{//方法必须定义在vue  的method中
            sayHi: function () {
                alert(this.message)
            }
        }
    });
</script>

</body>
</html>